1. Field of the Invention
The present invention relates generally to medical devices and methods. More particularly, the present invention relates to apparatus and methods for performing angioplasty, stent delivery, and related procedures using balloon catheters having ultrasonically oscillated surfaces which can impart energy to a blood vessel being treated.
Despite the growing sophistication of medical technology, vascular (blood vessel) diseases, such as acute myocardial infarction (heart attack) and peripheral arterial thrombosis (blood clots in leg arteries), remain a frequent, costly, and very serious problem in health care. Current methods of treatment, often expensive, are not always effective. In the U.S. alone, the cost of treatment and support and the loss of productivity due to vascular diseases together exceed $40 billion per year.
The core of the problem is that diseased sites within the blood vessels narrow and eventually become completely blocked as a result of the deposition of fatty materials, cellular debris, calcium, and/or blood clots, thereby blocking the vital flow of blood. Current treatments include drugs, interventional devices, and/or bypass surgery. High doses of thrombolytics (clot-dissolving drugs) are frequently used in an effort to dissolve the blood clots. Even with such aggressive therapy, thrombolytics fail to restore blood flow in the affected vessel in about 30% of patients. In addition, these drugs can also dissolve beneficial clots or injure healthy tissue causing potentially fatal bleeding complications.
While a variety of interventional devices are available, including angioplasty, atherectomy, and laser ablation catheters, the use of such devices to remove obstructing deposits may leave behind a wound that heals by forming a scar. The scar itself may eventually become a serious obstruction in the blood vessel (a process known as restenosis). Also, diseased blood vessels being treated with interventional devices sometimes develop vasoconstriction (elastic recoil), a process by which spasms or abrupt reclosures of the vessel occur, thereby restricting the flow of blood and necessitating further intervention. Approximately 40% of treated patients require additional treatment for restenosis resulting from scar formation occurring over a relatively long period, typically 4 to 12 months, while approximately 1-in-20 patients require treatment for vasoconstriction, which typically occurs from 4 to 72 hours after the initial treatment.
The use of ultrasonic energy has been proposed both to mechanically disrupt clot and to enhance the intravascular delivery of drugs to dissolve clot and inhibit restenosis. Ultrasonic energy may be delivered intravascularly using specialized catheters having an ultrasonically vibrating surface at or near their distal ends.
It would be desirable to provide improved devices, systems, and methods, for treating vascular diseases, particularly stenotic diseases which occlude the coronary and other arteries. In particular, it would be desirable to provide methods and devices for enhancing the performance of angioplasty procedures, where the ability to introduce an angioplasty catheter through a wholly or partly obstructed blood vessel lumen can be improved. Moreover, it would be desirable to provide mechanisms as part of an angioplasty catheter, which mechanisms can assist in initial balloon deployment and/or decrease the likelihood of subsequent clot formation and restenosis. The devices, systems, and methods, should further be useful with other procedures which employ balloon catheters, including stent deployment and drug delivery, where drug delivery can be achieved by deploying a pair of spaced-apart balloons for defining a treatment region therebetween.
The present invention relates generally to medical devices and methods. More particularly, the present invention relates to apparatus and methods for performing angioplasty, stent delivery, and related procedures using balloon catheters having ultrasonically oscillated surfaces which can impart energy to a blood vessel being treated.
Despite the growing sophistication of medical technology, vascular (blood vessel) diseases, such as acute myocardial infarction (heart attack) and peripheral arterial thrombosis (blood clots in leg arteries), remain a frequent, costly, and very serious problem in health care. Current methods of treatment, often expensive, are not always effective. In the U.S. alone, the cost of treatment and support and the loss of productivity due to vascular diseases together exceed $40 billion per year.
The core of the problem is that diseased sites within the blood vessels narrow and eventually become completely blocked as a result of the deposition of fatty materials, cellular debris, calcium, and/or blood clots, thereby blocking the vital flow of blood. Current treatments include drugs, interventional devices, and/or bypass surgery. High doses of thrombolytics (clot-dissolving drugs) are frequently used in an effort to dissolve the blood clots. Even with such aggressive therapy, thrombolytics fail to restore blood flow in the affected vessel in about 30% of patients. In addition, these drugs can also dissolve beneficial clots or injure healthy tissue causing potentially fatal bleeding complications.
While a variety of interventional devices are available, including angioplasty, atherectomy, and laser ablation catheters, the use of such devices to remove obstructing deposits may leave behind a wound that heals by forming a scar. The scar itself may eventually become a serious obstruction in the blood vessel (a process known as restenosis). Also, diseased blood vessels being treated with interventional devices sometimes develop vasoconstriction (elastic recoil), a process by which spasms or abrupt reclosures of the vessel occur, thereby restricting the flow of blood and necessitating further intervention. Approximately 40% of treated patients require additional treatment for restenosis resulting from scar formation occurring over a relatively long period, typically 4 to 12 months, while approximately 1-in-20 patients require treatment for vasoconstriction, which typically occurs from 4 to 72 hours after the initial treatment.
The use of ultrasonic energy has been proposed both to mechanically disrupt clot and to enhance the intravascular delivery of drugs to dissolve clot and inhibit restenosis. Ultrasonic energy may be delivered intravascularly using specialized catheters having an ultrasonically vibrating surface at or near their distal ends.
It would be desirable to provide improved devices, systems, and methods, for treating vascular diseases, particularly stenotic diseases which occlude the coronary and other arteries. In particular, it would be desirable to provide methods and devices for enhancing the performance of angioplasty procedures, where the ability to introduce an angioplasty catheter through a wholly or partly obstructed blood vessel lumen can be improved. Moreover, it would be desirable to provide mechanisms as part of an angioplasty catheter, which mechanisms can assist in initial balloon deployment and/or decrease the likelihood of subsequent clot formation and restenosis. The devices, systems, and methods, should further be useful with other procedures which employ balloon catheters, including stent deployment and drug delivery, where drug delivery can be achieved by deploying a pair of spaced-apart balloons for defining a treatment region therebetween.
2. Description of the Background Art
A catheter system having a pair of spaced-apart balloons with a coiled piezoelectric strip therebetween is described in U.S. Pat. No. 5,279,546. Catheters having elongate ultrasonic transmission elements and inflatable cuffs are described in U.S. Pat. Nos. 5,397,301; 5,304,115; and 4,870,953. A tunneling catheter having a radiofrequency, laser, or ultrasonic active distal end disposed within an angioplasty catheter is described in EP 189 329. An atherectomy catheter having an ultrasonically enhanced blade disposed adjacent an asymmetrically mounted balloon is described in U.S. Pat. No. 5,085,662. Phonophoresis transducers disposed within porous, inflatable balloons are suggested in U.S. Pat. Nos. 5,286,254 and 5,282,785. Other catheters having ultrasonic elements with the capability of delivering thrombolytic and other liquid agents are described in U.S. Pat. Nos. 5,362,309; 5,318,014; 5,315,998; 5,197,946; 5,380,273; 5,344,395; 5,342,292; 5,324,255; 5,269,297; 5,267,954; 4,808,153; 4,692,139; and 3,565,062; in WO 90/01300; and in Tachibana (1992) JVIR 3:299-303. A rigid ultrasonic probe intended for treating vascular plaque and having fluid delivery means is described in U.S. Pat. No. 3,433,226. An ultrasonic transmission wire intended for intravascular treatment is described in U.S. Pat. No. 5,163,421 and Rosenschein et al. (1990) JACC 15:711-717. Ultrasonic enhancement of systemic and localized drug delivery is described in U.S. Pat. Nos. 5,267,985; and 4,948,587; in WO 94/05361 and WO 91/19529; in JP 3-63041; and Yumita et al. (1990) Jpn. J. Cancer Res. 81:304-308. An electrosurgical angioplasty catheter having ultrasonic enhancement is described in U.S. Pat. No. 4,936,281. An infusion and drainage catheter having an ultrasonic cleaning mechanism is described in U.S. Pat. No. 4,698,058. Angioplasty balloon catheters having axial blade atherectomy, ultrasonic imaging, and rotary blade atherectomy devices at their distal ends are described in U.S. Pat. Nos. 5,053,044; 5,117,831; and 5,181,920, respectively.
This application is related to the following commonly assigned patents and applications: U.S. Pat. Nos. 5,725,494; 5,728,062; 5,735,811; 5,931,805; U.S. Pat. Nos. 09/033,834; 09/223,230; 09/635,033; and 09/653,678. The full disclosures of each of these patents and pending applications are incorporated herein by reference.
According to the present invention, improved devices and systems are provided which combine both an inflatable balloon and an axially oscillated interface surface on a single catheter device. The devices and systems are useful for a number of intervascular procedures, including (1) angioplasty and related procedures, such as stent deployment, where ultrasonic energy delivered by the interface surface can soften the stenotic material in the blood vessel to facilitate deployment and initial treatment and can also reduce residual clot in the treated region in order to lessen the likelihood of restenosis, and (2) drug delivery methods where balloons are used to isolate a treatment region and at least one of the balloons is coupled to the interface surface so that oscillation of the balloon(s) enhances mixing and penetration of a treatment medium localized between the balloons.
The catheters of the present invention will comprise a catheter body having a proximal end and a distal end. An oscillating driver is disposed at or near the distal end of the catheter body, and an interface surface is mechanically coupled to the driver so that the surface can be axially oscillated relative to the catheter body. An inflatable balloon is also disposed on the catheter body near the interface surface, where the balloon can be used for angioplasty, stent deployment, or the like, and optionally can be combined with a second balloon to define a drug treatment region therebetween.
In a first specific embodiment, the interface surface comprises a distal tip which extends laterally over the distal end of the catheter body. An angioplasty or stent delivery balloon is disposed on the catheter body proximal to the interface surface. Optionally, the interface surface can further include a cylindrical portion which extends over an axial surface of the catheter body. In either case, a distal end of the balloon can be secured directly to the interface surface so that the balloon itself is caused to directly oscillate as the interface surface is oscillated by the driver.
In use, the catheters having interface surfaces including a laterally disposed distal tip will facilitate penetration of the catheter through a partly or wholly occluded stenotic region within a blood vessel. The distal tip will be driven, and the catheter advanced through the stenotic material, with the ultrasonic energy softening the stenotic material to facilitate advance of the catheter. The balloon, which is proximal to the distal tip, may then be used for either an angioplasty procedure, stent delivery, or both. In either case, the interface surface on the catheter can thereafter be used to further treat the stenotic region with ultrasonic energy to reduce the amount of clot remaining in order to lessen the likelihood of further clot formation and restenosis.
In a second specific embodiment, the interface surface is disposed at least partly within the inflatable balloon on the catheter body. Preferably, the interface surface and associated oscillatory driver are both located entirely within the inflatable balloon, so that the interface surface can be used to transfer ultrasonic energy directly into the inflation medium used to inflate the balloon. Alternatively, the balloon is mounted so that at least one of its forward end and/or distal end is secured to a cylindrical interface surface. In this way, after balloon inflation, the interface surface will directly oscillate one or both ends of the balloon. The catheters of this type will be particularly useful for performing enhanced angioplasty procedures, optionally with stent delivery.
A third exemplary embodiment of the catheter of the present invention comprises a pair of spaced-apart inflatable balloons on the catheter body. A cylindrical interface surface is disposed between the balloons, with at least one of the distal end of the proximal-most balloon and the proximal end of the distal-most balloon being secured to the interface member. A fluid delivery lumen is provided within the catheter so that a treatment medium can be delivered to the region between the balloons when the balloons are expanded in a blood vessel. Mixing and/or penetration of the treatment medium is enhanced by ultrasonic oscillation of the cylindrical interface surface when the treatment medium is present.